Security researcher Hector Marco has uncovered an interesting attack that can be launched against users of some versions of the stock Android email app. Marco discovered that all an attacker has to do is send an email with a specially-crafted header, and they can cause the email Android app to crash. Reopening the app will just cause it to crash again, because every time the app attempts to download the malicious email it will keep triggering the same fault. This is, effectively, a denial of service attack, but not an attack which clogs up your website and causes it to fall over.”]
Source: https://grahamcluley.com/how-email-crash-android-gmail-app/